1. Field
Various communication systems may benefit from appropriate correlation of failure reports. For example, communication systems of the third generation partnership project (3GPP) may benefit from correlating radio link failure and minimization of drive test reports, particularly with respect to self-organized networks mobility robustness optimization.
2. Description of the Related Art
Radio Link Failure (RLF) reporting was introduced in third generation partnership project (3GPP) release 9 (Rel-9) under Self Organized Networks Mobility Robustness Optimization (SON MRO) feature. User equipment (UE) may experience a radio link failure either when moving from a first cell, Cell A, to a second cell, Cell B, attempting a hand off, or when experiencing a coverage hole. On experiencing radio link failure, a user equipment can log a snapshot of the last monitored radio frequency (RF) condition along with other information and stores it as a radio link failure report. Upon (re)establishing a connection to a cell, the user equipment can indicate the availability of a radio link failure report to the cell, which can retrieve the radio link failure report from the user equipment. If the cell is different from the cell where the radio link failure occurred, the new cell can forward this radio link failure report back to the cell where radio link failure occurred, as part of the X2 radio link failure indication message. The cell where radio link failure has occurred processes the radio link failure report as an input to the distributed SON MRO algorithm.
In 3GPP release 10 (Rel-10) the additional value of radio link failure reports to other features beside the distributed SON MRO were identified, which resulted in certain changes to the radio link failure reports content, such as addition of location information and various cell identifiers, and making their support mandatory on the UE. The radio link failure reports can be used in the detection of coverage holes and handover failure boundaries, as well as in assisting mobility drive tests and the like.
As of 3GPP Rel-10, two versions of the radio link failure reports exist: a release 9 version that does not contain location information and may only be interpreted by the cell where radio link failure has occurred; and a release 10 version that contains additional attributes such as location information and cell identities making it useful for centralized self-organized network (cSON).
Correlation requirement for radio link failure reporting and MDT reporting may be met, for example, by combining MDT and radio link failure to a single trace job. This approach, however, also imposes a user consent requirement on the radio link failure data.